Development of a chemiresistor sensor based on polyaniline (PANI) nanofibers for detection of ammonia

Abstract

Nanostructured conducting polymers have received great attention due to their unique properties and promising applications in nanomaterials and nanotechnology. Among them, nanostructured polyaniline (PANI) has been extensively studied due to its ease of synthesis, excellent conductivity, environmental stability, large surface area, and highly reversible redox properties. This study reports a development of a chemiresistor sensor based on PANI nanofibers for ammonia detection. The studies are divided into two parts, which are the preparation of PANI nanofibers at various parameters and the development of chemiresistor sensor for the detection of ammonia. The polymerization time, chemical structure, surface morphology, and electrical properties of the synthesized PANI nanofibers were characterized using digital watch, FTIR, UV-Vis, FESEM, SEM, and 4-point probe, respectively. The preparation of PANI through interfacial (IP-PANI) and rapid mixing polymerization (RP-PANI) give not significant difference except the polymerization time which was 390 and 300s, respectively. FTIR spectra analysis was corresponded to well-doped PANI with the existence of peaks at 3286, 1580, 1490, 1218, 1146 and 620 cm-1, respectively, which are related to N-H, C=C, C-N, in-plane C-H, and out-plane C-H functional group. UV-Vis spectra of the PANI nanofibers showed that three band transitions were appeared at 340, 420, and 814 nm, respectively, which refered to π-π*, polaron-π*, and localized polaron band while the average diameter size of PANI nanofibers for both methods was ~ 70nm. The effect of hydrochloric acid (HCl) concentration and ammonium persulfate/aniline (APS/ANI) molar ratio on PANI nanofibers synthesized by rapid mixing polymerization were also studied.